1. Field
Various embodiments relate to a rotary valve including a rotor which is rotated to open and close a flow passage.
2. Description of Related Art
In an engine (internal combustion engine) of a vehicle such as an automobile, for the purpose of enhancing the warm-up performance of the engine, enhancing the fuel efficiency by operating the engine at an optimal temperature, and the like, it is considered that a bypass passage through which cooling water bypasses a radiator and is returned to the engine as it is provided separately from a main passage through which the cooling water is circulated between the engine and the radiator, a cooling water control valve is provided in the main passage, and by controlling the opening degree of the cooling water control valve according to the temperature of the cooling water and the other values, the amount of the cooling water which flows through the main passage and is cooled by the radiator is controlled. Note that, the cooling water is circulated by a pump driven by the engine, and during an operation of the engine, the cooling water is mainly circulated through the main passage in a case where the cooling water control valve is opened, and is circulated through the bypass passage in a case where the cooling water control valve is closed.
For example, during the start-up of the engine at a low cooling water temperature, the main passage is blocked to allow the cooling water to return to the engine as it is from the bypass passage without passing through the radiator, thereby accelerating the warm-up of the engine. In addition, for example, in order to control the temperature of the cooling water to optimize the combustion of a fuel in the engine even after the warm-up, opening and closing (the opening degree) of the cooling water control valve is adjusted.
In the cooling water control valve, the use of a rotary valve or the like is considered.
In the rotary valve, for example, a flow passage is provided in a rotor, and in a housing which accommodates the rotor, an opening which is connected to an external flow passage and communicates with the flow passage in the rotor in a case where the angle of the rotor is an angle at which the rotor is opened is formed.
In addition, a seal is disposed between the opening of the housing and an opening of the flow passage of the rotor such that distribution of flowing water can be efficiently performed even when there is a gap between the openings.
For example, a structure in which a large gap is provided between the opening of the housing and the opening of the rotor and a packing is disposed therebetween is suggested (for example, refer to Patent Literature 1).
The packing is formed in a cylindrical shape in which both ends are open, one end portion serves as a seal for the opening of the rotor, and the other open end serves as a seal for the opening of the housing. In Patent Literature 1, the outer circumferential surface of the rotor and the inner circumferential surface of a part of the housing that accommodates the rotor are formed in cylindrical shapes, and the distance between the seal on the housing side and the seal on the rotor side is substantially constant at any position along the circumferential direction of the openings of the housing and the rotor.
Note that, for example, in a case where the inner surface which is provided with the opening on the housing side and opposes the rotor is a flat surface, the seal on the housing side has a flat surface shape, and the seal on the rotor side has a cylindrical surface shape. For this reason, the distance between the seals varies depending on the position in the circumferential direction. In this case, the length of a rubber as the packing disposed between the seals varies, and thus surface pressure applied to the seal from a surface that abuts on the seal varies with position. Therefore, there is concern that the function of the seal may not be sufficiently exhibited. As described above, by causing the distance between the seals to rarely change with position, the surface pressure can be allowed to be substantially constant even at different positions in the circumferential direction of the seal.
3. Patent Literature
Patent Literature 1: Japanese Publication No. 2000-193104 A